Ask Nick: Worn rims, shaving and more on seat alignment

Nick Legan answers reader questions on replacing worn rims, a unique chain holder for bike washing and aero whiskers

Photo: Mark Johnson

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Editor’s Note: VeloNews tech editor Nick Legan is a former ProTour mechanic who most recently wrenched for Team RadioShack at the 2010 Tour de France and elsewhere. His column appears here every Thursday. You can submit questions to Nick at, and be sure to check out Nick’s previous columns.
First, some follow-up on getting saddles straight. I received several emails with different suggestions for getting them in line with your bike. Here’s my favorite:

I was reading over last week’s post and I saw the issue of straight saddles come up. Personally I take a cloth measuring tape (but one could use a piece of dental floss), string it between the head of the seat post and the steerer tube. Gives you an easy-to-compare, perfectly straight line to line it all up with.  On a side note floss can be used in a pinch for the best tools… my plumb-bob consists of floss and a spoke wrench.
— Jordan Oroshiba

I saw in Sunday’s Giro time trial finale that the third place GC finisher Thomas de Gendt has what looks to be at least a week’s worth of whiskers on his face. Maybe he didn’t shave for the whole Giro? Just curious in this age of wind tunnels and expensive aero bits that maybe he could have, ahem, shaved microseconds off his time, if those whiskers had been removed before the TT?
— Ken Press

A. Ken,
It’s a good question and one that I can’t answer definitively. I would bet that it varies from rider to rider. It’s incredible to see what makes one rider faster in the tunnel while the same thing slows another.

Many old-school Euros believe that you shouldn’t shave before an important race day as the body uses energy growing the whiskers back. Seems like a bunch of malarkey to me. Whiskers are always growing! Of course, there is the supreme effort of actually shaving. That could certainly drain you of your powers. I mean, have you seen the arms on some pros? They look like a tyrannosaurus rex: huge legs and micro arms. The act of lifting their arms too many times might render them bed-ridden.

I have a question on rim wear.  I have been hearing recently about brake surface wear on rims and it has put up a red flag that is always in the back of my mind now.  I am riding Mavic CXP 21 rims that are about 12 years old.  They’ve only seen about six years of 2,0000-3,000 miles of use but this is in Pennsylvania with lots of wet riding and dirty roads.  I try to keep my brake pads as clean as possible but sometimes I hear that nagging sound of a small piece of grit in the pads on the rim.  Today I did some rim inspection.  My 21mm rims only checked 19.89 wide and as best as I could check, some places of the rim the actual width is only about 1.2mm.  The front rim is not as bad at 20.23mm.  I went to the Mavic website to try to find any information on rim wear and tolerances, but can’t seem to find anything.  The closest I could find was something along the lines of “0.4mm max rim wear.”  If that is true, I appear to be way beyond time for replacement on these rims.  Is it time for some new rims?
— Tim Wright

A. Tim,
Your question is a good one. Many riders/readers are probably riding around on heavily worn rims. It’s good that you pay attention to them. Cleaning your pads certainly will slow the wear of your rims. Keep that up.

I got in touch with Zack Vestal at Mavic and there’s some good news. I don’t think that your rims were originally 21mm wide. Vestal was unable to find the exact specs for the CXP21, but he thinks they were no wider than 20mm when new. And that fits with my memory of the rim. Of course, your measurement on your rear rim leads me to believe they were wider than 20mm.

While the CXP21 model doesn’t have built-in rim wear indicators like more recent models, the Mavic models with them have a depth of 1mm on each side. So even if your rims were 21mm, you haven’t worn through 1mm on each side.

On a heavily worn rim the braking surface will be concave because pads are rarely the height of the entire braking surface. Your fingers will often feel it even if your eyes can’t see it. So keep checking your rims, but I think you’re safe for the moment. If you still have your doubts, you can’t go wrong with running it by your shop for a look.

I follow a bunch of the pro teams on Facebook and love the different articles and pictures that they post daily.  I saw a gallery this morning from Team Sky dedicated to their hard working mechanics.  I noticed in the pictures that they have a chain guide that installs in one dropout so that you can run the chain to clean it.  I figured by the color of the part that it is made by Park Tool.  Upon searching the Park Tool site I could find nothing that matches.  Have you ever seen this part before or is it something new or something their mechanics came up with?  If it’s the last I love the DIY challenge.
— Brendan Stuk

A. Brendan,
What you’ve spotted is a very handy tool from Morgan Blue, a European lube/degreaser/massage oil manufacturer. It’s a very simple chain guide made of plastic with a lag bolt and wing nut to tighten in on the inside of the driveside rear dropout. Morgan Blue supplies them to its sponsored teams. I actually have one and use it when I wash bikes. If you’re at a race, you can try to trade with a mechanic for one. A six-pack of beer would probably work. You could also try to get in touch with Morgan Blue. It’s part of the Maintenance Kit online.

You could also make one yourself. It’s a matter of turning a piece of plastic on a lathe. I’ve also seen mechanics make them using a rear quick release axle and spacers. Pedro’s makes its $13 Chain Keeper, but it’s never been my favorite. I hear tell from a Boulder-based cyclocrosser that he has a killer one in the works. As soon as it’s ready, I’ll let you know via

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